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-rw-r--r--db2/lock/lock_deadlock.c496
1 files changed, 496 insertions, 0 deletions
diff --git a/db2/lock/lock_deadlock.c b/db2/lock/lock_deadlock.c
new file mode 100644
index 0000000000..54a73afd1b
--- /dev/null
+++ b/db2/lock/lock_deadlock.c
@@ -0,0 +1,496 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996, 1997
+ *	Sleepycat Software.  All rights reserved.
+ */
+
+#include "config.h"
+
+#ifndef lint
+static const char copyright[] =
+"@(#) Copyright (c) 1997\n\
+	Sleepycat Software Inc.  All rights reserved.\n";
+static const char sccsid[] = "@(#)lock_deadlock.c	10.20 (Sleepycat) 8/21/97";
+#endif
+
+#ifndef NO_SYSTEM_INCLUDES
+#include <sys/types.h>
+
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#endif
+
+#include "db_int.h"
+#include "shqueue.h"
+#include "db_shash.h"
+#include "lock.h"
+#include "common_ext.h"
+
+#define	ISSET_MAP(M, N)	(M[(N) / 32] & (1 << (N) % 32))
+
+#define	CLEAR_MAP(M, N) {						\
+	u_int32_t __i;							\
+	for (__i = 0; __i < (N); __i++)					\
+		M[__i] = 0;						\
+}
+
+#define	SET_MAP(M, B)	(M[(B) / 32] |= (1 << ((B) % 32)))
+#define	CLR_MAP(M, B)	(M[(B) / 32] &= ~(1 << ((B) % 32)))
+
+#define	OR_MAP(D, S, N)	{						\
+	u_int32_t __i;							\
+	for (__i = 0; __i < (N); __i++)					\
+		D[__i] |= S[__i];					\
+}
+#define	BAD_KILLID	0xffffffff
+
+typedef struct {
+	int		valid;
+	u_int32_t	id;
+	DB_LOCK		last_lock;
+} locker_info;
+
+static int  __dd_abort __P((DB_ENV *, locker_info *));
+static int  __dd_build __P((DB_ENV *, u_int32_t **, int *, locker_info **));
+#ifdef DEBUG
+static void __dd_debug __P((DB_ENV *, locker_info *, u_int32_t *, int));
+#endif
+static u_int32_t
+	   *__dd_find __P((u_int32_t *, locker_info *, u_int32_t));
+
+int
+lock_detect(lt, flags, atype)
+	DB_LOCKTAB *lt;
+	int flags;
+	u_int32_t atype;
+{
+	DB_ENV *dbenv;
+	locker_info *idmap;
+	u_int32_t *bitmap, *deadlock, killid;
+	int do_pass, i, nlockers, nentries, ret;
+
+	/* Validate arguments. */
+	if ((ret =
+	    __db_fchk(lt->dbenv, "lock_detect", flags, DB_LOCK_CONFLICT)) != 0)
+		return (ret);
+
+	/* Check if a detector run is necessary. */
+	do_pass = 1;
+	dbenv = lt->dbenv;
+	if (LF_ISSET(DB_LOCK_CONFLICT)) {
+		/* Make a pass every time a lock waits. */
+		LOCK_LOCKREGION(lt);
+		do_pass = dbenv->lk_info->region->need_dd != 0;
+		UNLOCK_LOCKREGION(lt);
+	}
+
+	if (!do_pass)
+		return (0);
+
+	/* Build the waits-for bitmap. */
+	if ((ret = __dd_build(dbenv, &bitmap, &nlockers, &idmap)) != 0)
+		return (ret);
+
+	if (nlockers == 0)
+		return (0);
+#ifdef DEBUG
+	if (dbenv->db_verbose != 0)
+		__dd_debug(dbenv, idmap, bitmap, nlockers);
+#endif
+	/* Find a deadlock. */
+	deadlock = __dd_find(bitmap, idmap, nlockers);
+	nentries = ALIGN(nlockers, 32) / 32;
+	killid = BAD_KILLID;
+	if (deadlock != NULL) {
+		/* Kill someone. */
+		switch (atype) {
+		case DB_LOCK_OLDEST:
+			/*
+			 * Find the first bit set in the current
+			 * array and then look for a lower tid in
+			 * the array.
+			 */
+			for (i = 0; i < nlockers; i++)
+				if (ISSET_MAP(deadlock, i))
+					killid = i;
+
+			if (killid == BAD_KILLID) {
+				__db_err(dbenv,
+				    "warning: could not find %s",
+				    "locker to abort");
+				break;
+			}
+
+			/*
+			 * The oldest transaction has the lowest
+			 * transaction id.
+			 */
+			for (i = killid + 1; i < nlockers; i++)
+				if (ISSET_MAP(deadlock, i) &&
+				    idmap[i].id < idmap[killid].id)
+					killid = i;
+			break;
+		case DB_LOCK_DEFAULT:
+		case DB_LOCK_RANDOM:
+			/*
+			 * We are trying to calculate the id of the
+			 * locker whose entry is indicated by deadlock.
+			 * We know that this is less than nlockers, so
+			 * the cast below is valid.
+			 */
+			killid =
+			    (u_int32_t)((deadlock - bitmap) / nentries);
+			break;
+		case DB_LOCK_YOUNGEST:
+			/*
+			 * Find the first bit set in the current
+			 * array and then look for a lower tid in
+			 * the array.
+			 */
+			for (i = 0; i < nlockers; i++)
+				if (ISSET_MAP(deadlock, i))
+					killid = i;
+
+			if (killid == BAD_KILLID) {
+				__db_err(dbenv,
+				    "warning: could not find %s",
+				    "locker to abort");
+				break;
+			}
+			/*
+			 * The youngest transaction has the highest
+			 * transaction id.
+			 */
+			for (i = killid + 1; i < nlockers; i++)
+				if (ISSET_MAP(deadlock, i) &&
+				    idmap[i].id > idmap[killid].id)
+					killid = i;
+			break;
+		default:
+			killid = BAD_KILLID;
+			ret = EINVAL;
+		}
+
+		/* Kill the locker with lockid idmap[killid]. */
+		if (dbenv->db_verbose != 0 && killid != BAD_KILLID)
+			__db_err(dbenv, "Aborting locker %lx",
+			    (u_long)idmap[killid].id);
+
+		if (killid != BAD_KILLID &&
+		    (ret = __dd_abort(dbenv, &idmap[killid])) != 0)
+			__db_err(dbenv,
+			    "warning: unable to abort locker %lx",
+			    (u_long)idmap[killid].id);
+	}
+	free(bitmap);
+	free(idmap);
+
+	return (ret);
+}
+
+/*
+ * ========================================================================
+ * Utilities
+ */
+static int
+__dd_build(dbenv, bmp, nlockers, idmap)
+	DB_ENV *dbenv;
+	u_int32_t **bmp;
+	int *nlockers;
+	locker_info **idmap;
+{
+	DB_LOCKTAB *lt;
+	DB_LOCKOBJ *op, *lockerp;
+	struct __db_lock *lp;
+	u_int32_t *bitmap, count, *entryp, i, id, nentries, *tmpmap;
+	locker_info *id_array;
+	int is_first, ret;
+
+	lt = dbenv->lk_info;
+
+	/*
+	 * We'll check how many lockers there are, add a few more in for
+	 * good measure and then allocate all the structures.  Then we'll
+	 * verify that we have enough room when we go back in and get the
+	 * mutex the second time.
+	 */
+	LOCK_LOCKREGION(lt);
+retry:	count = lt->region->nlockers;
+	lt->region->need_dd = 0;
+	UNLOCK_LOCKREGION(lt);
+
+	if (count == 0) {
+		*nlockers = 0;
+		return (0);
+	}
+
+	if (dbenv->db_verbose)
+		__db_err(dbenv, "%lu lockers", (u_long)count);
+
+	count += 10;
+	nentries = ALIGN(count, 32) / 32;
+	/*
+	 * Allocate enough space for a count by count bitmap matrix.
+	 *
+	 * XXX
+	 * We can probably save the malloc's between iterations just
+	 * reallocing if necessary because count grew by too much.
+	 */
+	if ((bitmap = (u_int32_t *)calloc((size_t)count,
+	    sizeof(u_int32_t) * nentries)) == NULL) {
+		__db_err(dbenv, "%s", strerror(ENOMEM));
+		return (ENOMEM);
+	}
+
+	if ((tmpmap =
+	    (u_int32_t *)calloc(sizeof(u_int32_t), nentries)) == NULL) {
+		__db_err(dbenv, "%s", strerror(ENOMEM));
+		free(bitmap);
+		return (ENOMEM);
+	}
+
+	if ((id_array = (locker_info *)calloc((size_t)count,
+	    sizeof(locker_info))) == NULL) {
+		__db_err(dbenv, "%s", strerror(ENOMEM));
+		free(bitmap);
+		free(tmpmap);
+		return (ENOMEM);
+	}
+
+	/*
+	 * Now go back in and actually fill in the matrix.
+	 */
+	LOCK_LOCKREGION(lt);
+	if (lt->region->nlockers > count) {
+		free(bitmap);
+		free(tmpmap);
+		free(id_array);
+		goto retry;
+	}
+
+	/*
+	 * First we go through and assign each locker a deadlock detector id.
+	 * Note that we fill in the idmap in the next loop since that's the
+	 * only place where we conveniently have both the deadlock id and the
+	 * actual locker.
+	 */
+	for (id = 0, i = 0; i < lt->region->table_size; i++)
+		for (op = SH_TAILQ_FIRST(&lt->hashtab[i], __db_lockobj);
+		    op != NULL; op = SH_TAILQ_NEXT(op, links, __db_lockobj))
+			if (op->type == DB_LOCK_LOCKER)
+				op->dd_id = id++;
+	/*
+	 * We go through the hash table and find each object.  For each object,
+	 * we traverse the waiters list and add an entry in the waitsfor matrix
+	 * for each waiter/holder combination.
+	 */
+	for (i = 0; i < lt->region->table_size; i++) {
+		for (op = SH_TAILQ_FIRST(&lt->hashtab[i], __db_lockobj);
+		    op != NULL; op = SH_TAILQ_NEXT(op, links, __db_lockobj)) {
+			if (op->type != DB_LOCK_OBJTYPE)
+				continue;
+			CLEAR_MAP(tmpmap, nentries);
+
+			/*
+			 * First we go through and create a bit map that
+			 * represents all the holders of this object.
+			 */
+			for (lp = SH_TAILQ_FIRST(&op->holders, __db_lock);
+			    lp != NULL;
+			    lp = SH_TAILQ_NEXT(lp, links, __db_lock)) {
+				if ((errno = __lock_getobj(lt, lp->holder,
+				    NULL, DB_LOCK_LOCKER, &lockerp)) != 0) {
+					__db_err(dbenv,
+					    "warning unable to find object");
+					continue;
+				}
+				id_array[lockerp->dd_id].id = lp->holder;
+				id_array[lockerp->dd_id].valid = 1;
+
+				/*
+				 * If the holder has already been aborted, then
+				 * we should ignore it for now.
+				 */
+				if (lp->status == DB_LSTAT_HELD)
+					SET_MAP(tmpmap, lockerp->dd_id);
+			}
+
+			/*
+			 * Next, for each waiter, we set its row in the matrix
+			 * equal to the map of holders we set up above.
+			 */
+			for (is_first = 1,
+			    lp = SH_TAILQ_FIRST(&op->waiters, __db_lock);
+			    lp != NULL;
+			    is_first = 0,
+			    lp = SH_TAILQ_NEXT(lp, links, __db_lock)) {
+				if ((ret = __lock_getobj(lt,
+				    lp->holder, NULL, DB_LOCK_LOCKER, &lockerp))
+				    != 0) {
+					__db_err(dbenv,
+					    "warning unable to find object");
+					continue;
+				}
+				id_array[lockerp->dd_id].id = lp->holder;
+				id_array[lockerp->dd_id].valid = 1;
+
+				/*
+				 * If the transaction is pending abortion, then
+				 * ignore it on this iteration.
+				 */
+				if (lp->status != DB_LSTAT_WAITING)
+					continue;
+
+				entryp = bitmap + (nentries * lockerp->dd_id);
+				OR_MAP(entryp, tmpmap, nentries);
+				/*
+				 * If this is the first waiter on the queue,
+				 * then we remove the waitsfor relationship
+				 * with oneself.  However, if it's anywhere
+				 * else on the queue, then we have to keep
+				 * it and we have an automatic deadlock.
+				 */
+				if (is_first)
+					CLR_MAP(entryp, lockerp->dd_id);
+			}
+		}
+	}
+
+	/* Now for each locker; record its last lock. */
+	for (id = 0; id < count; id++) {
+		if (!id_array[id].valid)
+			continue;
+		if ((ret = __lock_getobj(lt,
+		    id_array[id].id, NULL, DB_LOCK_LOCKER, &lockerp)) != 0) {
+			__db_err(dbenv,
+			    "No locks for locker %lu", (u_long)id_array[id].id);
+			continue;
+		}
+		lp = SH_LIST_FIRST(&lockerp->heldby, __db_lock);
+		if (lp != NULL)
+			id_array[id].last_lock = LOCK_TO_OFFSET(lt, lp);
+	}
+
+	/* Pass complete, reset the deadlock detector bit. */
+	lt->region->need_dd = 0;
+	UNLOCK_LOCKREGION(lt);
+
+	/*
+	 * Now we can release everything except the bitmap matrix that we
+	 * created.
+	 */
+	*nlockers = id;
+	*idmap = id_array;
+	*bmp = bitmap;
+	free(tmpmap);
+	return (0);
+}
+
+static u_int32_t *
+__dd_find(bmp, idmap, nlockers)
+	u_int32_t *bmp;
+	locker_info *idmap;
+	u_int32_t nlockers;
+{
+	u_int32_t i, j, nentries, *mymap, *tmpmap;
+
+	/*
+	 * For each locker, or in the bits from the lockers
+	 * on which that locker is waiting.
+	 */
+	nentries = ALIGN(nlockers, 32) / 32;
+	for (mymap = bmp, i = 0; i < nlockers; i++, mymap += nentries) {
+		if (!idmap[i].valid)
+			continue;
+		for (j = 0; j < nlockers; j++) {
+			if (ISSET_MAP(mymap, j)) {
+				/* Find the map for this bit. */
+				tmpmap = bmp + (nentries * j);
+				OR_MAP(mymap, tmpmap, nentries);
+				if (ISSET_MAP(mymap, i))
+					return (mymap);
+			}
+		}
+	}
+	return (NULL);
+}
+
+static int
+__dd_abort(dbenv, info)
+	DB_ENV *dbenv;
+	locker_info *info;
+{
+	DB_LOCKTAB *lt;
+	DB_LOCKOBJ *lockerp, *sh_obj;
+	struct __db_lock *lockp;
+	int ret;
+
+	lt = dbenv->lk_info;
+	LOCK_LOCKREGION(lt);
+
+	/* Find the locker's last lock. */
+	if ((ret =
+	    __lock_getobj(lt, info->id, NULL, DB_LOCK_LOCKER, &lockerp)) != 0)
+		goto out;
+
+	lockp = SH_LIST_FIRST(&lockerp->heldby, __db_lock);
+	if (LOCK_TO_OFFSET(lt, lockp) != info->last_lock ||
+	    lockp == NULL || lockp->status != DB_LSTAT_WAITING)
+		goto out;
+
+	/* Abort lock, take it off list, and wake up this lock. */
+	lockp->status = DB_LSTAT_ABORTED;
+	lt->region->ndeadlocks++;
+	SH_LIST_REMOVE(lockp, locker_links, __db_lock);
+	sh_obj = (DB_LOCKOBJ *)((u_int8_t *)lockp + lockp->obj);
+	SH_TAILQ_REMOVE(&sh_obj->waiters, lockp, links, __db_lock);
+        (void)__db_mutex_unlock(&lockp->mutex, lt->fd);
+
+	ret = 0;
+
+out:	UNLOCK_LOCKREGION(lt);
+	return (ret);
+}
+
+#ifdef DEBUG
+static void
+__dd_debug(dbenv, idmap, bitmap, nlockers)
+	DB_ENV *dbenv;
+	locker_info *idmap;
+	u_int32_t *bitmap;
+	int nlockers;
+{
+	u_int32_t *mymap;
+	int i, j, nentries;
+	char *msgbuf;
+
+	__db_err(dbenv, "Waitsfor array");
+	__db_err(dbenv, "waiter\twaiting on");
+	/*
+	 * Alloc space to print 10 bytes per item waited on.
+	 */
+	if ((msgbuf = (char *)malloc((nlockers + 1) * 10 + 64)) == NULL) {
+		errno = ENOMEM;
+		__db_err(dbenv, "%s", strerror(errno));
+		return;
+	}
+
+	nentries = ALIGN(nlockers, 32) / 32;
+	for (mymap = bitmap, i = 0; i < nlockers; i++, mymap += nentries) {
+		if (!idmap[i].valid)
+			continue;
+		sprintf(msgbuf, "%lx\t\t", (u_long)idmap[i].id);/* Waiter. */
+		for (j = 0; j < nlockers; j++)
+			if (ISSET_MAP(mymap, j))
+				sprintf(msgbuf, "%s %lx", msgbuf,
+				    (u_long)idmap[j].id);
+		(void)sprintf(msgbuf,
+		    "%s %lu", msgbuf, (u_long)idmap[i].last_lock);
+		__db_err(dbenv, msgbuf);
+	}
+
+	free(msgbuf);
+}
+#endif